Process for the manufacture of a plastic component with a seal, and assembly unit

ABSTRACT

A plastic component, usable in a combustion engine, is made by forming an elastomeric seal onto at least one support element. The support element, complete with the seal, is placed in a cavity or fixture of a plastic injection mold, and the plastic component is created only by forming plastic material onto the support element. The finished plastic component with the molded-on seal is removed from the cavity.

[0001] This invention claims priority to German Patent Application No.103 14 033.6, filed Mar. 28, 2003.

BACKGROUND OF THE INVENTION

[0002] 1. Technical Field

[0003] The invention consists of a process for the manufacture of aplastic component, usable in a combustion engine, connected effectivelywith an elastomeric seal.

[0004] 2. Related Art

[0005] A plastic cover, made by injection molding, and made of at leasttwo different plastics, can be seen in EP-A 0665370. The cover can beeffectively connected with an elastomeric seal. A stiffening material isnot indicated between the seal and the plastic cover. In EP-B 0860602, aprocess for the manufacture of a cylinder head cover for a combustionengine, as well as a cylinder head cover, is described. The cylinderhead cover is made using the following process steps:

[0006] Forming the cover component out of plastic

[0007] Activation of an opposing surface of the seal, in the covercomponent, by coronal treatment

[0008] Application of adhesive on the activated surface of the sealand/or a corresponding surface on the cover component

[0009] Placing the cover component and the seal in a heatable,pre-warmed adhesive fixture

[0010] Holding the adhesive fixture in a closed condition for aprescribed time at a prescribed temperature, and

[0011] Removing the finished cylinder head cover from the adhesivefixture.

[0012] The seal, which is provided with a support element, is createdindependently from the cover, so that two different molds are needed tomake the individual parts, and a further mold is needed to accept bothelements, before an effective connection of the two elements can beachieved.

[0013] A cover fixture for closing off motor housings can be seen inDE-A 196 233 36, in particular a valve cover fixture for the cylinderhead of a motor vehicle motor. The cover fixture contains a valve coveras well as an elastically bending seal that is seated in a groove thatruns around the surface of the valve cover that is oriented toward thecylinder head. A seal holder that can be connected to the valve cover,and which holds the shape of the seal that can be attached between thegroove floor and the cylinder head, is provided with pass-throughopenings for the seal.

[0014] For components that are made of plastic, such as covers, lids, orsimilar, due to the properties of larger tolerances relative to metalcovers, the seals have to be able to adapt more. This is based largelyon the lower stiffness and larger relaxation and modifying influencesthan with metal covers.

SUMMARY OF THE INVENTION

[0015] The invention addresses the task of preparing a process formanufacturing a plastic component that can be used in the area of acombustion engine, and is connected to an elastomeric seal. The processwill no longer have the problems associated with this type of componentafter it is made, and thereby will lead to a longer lifespan of theplastic components that are effectively connected to the sealingelements.

[0016] The task is solved by a process for manufacturing a plasticcomponent that can be used in the area of a combustion engine, and isconnected to an elastomeric seal, that contains the following processsteps:

[0017] The elastomeric seal is formed onto at least one support element;the support element, complete with the seal, is placed in a cavity ormold of a plastic injection tool, and the plastic component is createdonly by forming plastic material onto the support element; the finishedplastic component with the molded-on seal is removed from the tool.

[0018] Advantageous extensions of the process described in the inventionare to be seen in the associated process-related sub-claims.

[0019] Also suggested is an assembly unit, made up of a plasticcomponent that can be used in the area of a combustion engine, and isconnected to an elastomeric seal, manufactured using a process adheringto one of the process-related claims.

[0020] Advantageous extensions of the assembly unit are to be seen inthe associated objective claims.

[0021] With the object of the invention, a new technical thought isdescribed for the creation of a sealing system, consisting of a plasticcomponent such as a plastic cover, lid, or similar, effectivelyconnected to an elastomeric seal. The object of the invention isdistinguished from the state of the technology by its simplifiedprocessing steps, where the required stiffness of the system is providedby the preferably metal support element. The plastic component, such asthe cylinder head cover, lid, or similar, can thereby have a simplerdesign.

[0022] Instead of a metal support component, other materials withselectable stiffness can be used.

[0023] After the processing steps described in the invention have beencarried out, one has a plastic component, such as a cylinder head cover,a lid, or similar, with an attached, preferably molded-on, seal withmetal reinforcement. The following advantages are attained by theinvention:

[0024] The plastic component, such as the cylinder head cover, the lid,or similar, can be mounted using the metal support element directly;screwed on, for instance. The use of inserts, such as bushings, is nolonger necessary.

[0025] The support element can be made as stiff as desired, so thatvarious applications can be addressed.

[0026] The negative properties of the plastic material, with regard tothe sealing system, are compensated for by the support element.

[0027] By using the support element, screw points are not needed.

[0028] The basic system can also be used with a disconnected sealingsystem.

[0029] Any necessary tempering processes for the elastomeric materialsdo not have to be done together with the entire component, but only withthe support element. Since the inherent stiffness is determined largelyby the support element, the plastic component, such as the cylinder headcover, the lid, or similar, can be made more simply.

THE DRAWINGS

[0030] The object of the invention is represented in the drawing as asample application, and described as follows. Shown are:

[0031]FIG. 1 Section through a plastic cylinder head for a combustionengine, containing a molded-on elastomeric seal;

[0032]FIG. 2 Partial representation of a leg of the cylinder head covercontaining the seal.

[0033] FIGS. 3 to 5 Variants of FIG. 2.

DETAILED DESCRIPTION

[0034]FIG. 1 shows a section through a plastic component 1, shown inthis example as a cylinder head cover, that is to have two legs 2, 3. Inthe end areas of the leg 2, 3, an elastomeric seal 5 is molded onto asupport element.

[0035]FIG. 2 shows an enlarged view of the leg 2 of the cylinder headcover 1. A support element 4 with a rectangular cross section can beseen in this example; formed only on it is an elastomeric sealingelement 5 complete with sealing lip 6. The cylinder head cover 1 is madeby first molding the elastomeric seal 5 on the support element 4, whichis metal in this example. In a subsequent step, the support element 4containing the elastomeric seal 5 is placed in a cavity or mold of aplastic injection molding machine, and the cylinder head cover 1 iscreated solely by injection of plastic material, solely onto the supportelement 4. In this example, a connection is to be brought about betweenthe leg 2 and the support element 4 via chemical bonding processes, suchas by the use of an adhesive or similar.

[0036] FIGS. 3 to 5 show variants of FIG. 2.

[0037] In FIG. 3, the support element 4 has a U-shaped sectionalprofile. The same can also be made as a strong plastic element that haspass-through openings 7. As previously addressed, the seal 5 is firstinjected onto the support element 4. After placing the support element 4in the appropriately shaped cavity of the plastic injection moldingmachine, the leg 2 of the cylinder head cover being made is injectedonto the U-shaped profile 4 only; namely, on its internal profile.

[0038] A mechanical connection (interlocking) between support element 4and leg 2 takes place via the pass-through openings 7.

[0039]FIG. 4 shows an alternative to FIG. 3. The metal support elementused in this example has an L-shaped cross section, and is also providedwith pass-through openings 7′. The sequence of the connection betweensupport element 4 and elastomeric seal 5 takes place analogously to thefigures described previously. The cylinder head cover containing the leg2 is subsequently injected onto it, while a mechanical interlock betweenthe support element 4 and the leg 2 is created via the pass-throughopenings 7′.

[0040]FIG. 5 shows a further alternative to FIG. 3. A metallic supportelement 4 can be seen, which in this example has a right-angle crosssection. The seal 5 is sprayed in place on the longer leg. The short,vertically running leg has openings that create angled tongues 8. Thetongues 8 are bent in alternating directions here, so that bent metaledge sections are formed across from each other. Through this means, agood mechanical connection (interlock) between the support element 4 andleg 2 is achieved.

1. A method of making a plastic component having a sealing feature,comprising: forming a subassembly of an elastomeric seal member securedto a support element; disposing the subassembly in a mold; formingplastic material in the mold and connecting plastic material to thesupport element to thereby form the plastic component; and removing thefinished plastic component from the mold complete with the supportelement and seal attached.
 2. The method of claim 1, wherein the plasticmaterial is injected onto the support element, which is made as a metalcomponent.
 3. The method of claim 1, wherein the connection between thesupport element and the plastic component is achieved by chemicalbonding.
 4. The method of claim 1, wherein the connection between thesupport element and the plastic component is achieved by mechanicaljoining.
 5. The method of claim 1, wherein the plastic component is madeas a cylinder head cover with legs, where the support element isprovided in the free end areas of the legs.
 6. The method of claim 1,including tempering the elastomeric seal at the time it is secured tothe support element.
 7. A plastic component assembly, comprising: anelastomeric seal member; a support element to which the seal member issecured; and a plastic component formed in-place against and attached tothe support element.
 8. The assembly of claim 7, wherein the supportelement is shaped with a profile, and is provided with pass-throughopenings, inserts, or bent tongues to provide a mechanical connectionbetween legs of the plastic component and the support element.
 9. Theassembly of claim 7, wherein the support element is made of metal. 10.The assembly of claim 7, wherein the plastic component comprises acylinder head cover with legs where the support element is located atend areas of the legs.
 11. The assembly of claim 7, wherein the supportelement has a right angle or U-shaped profile.
 12. The assembly of claim8, wherein the pass-through openings, inserts, or tongues are providedin the area of the parts of the support element that are oriented towardthe associated legs of the cylinder head cover.